1. Field of the Invention
The present invention relates to a display device, a portable electronic device and a method of controlling a display device, in particular to a back-light display device, a portable electronic device and a method of controlling a display device capable of developing a desired color for display.
2. Description of the Related Art
A conventional red (R), green (G) and blue (B) back-light display is disclosed in Japanese Patent Laid-Open No. 7-281647.
This conventional RGB back-light display intends to avoid degradation of image quality resulting from a color fringe or after-image. The color fringe or after-image, for example, may arise when red (R) and green (G) colors intermingle with each other by failing to smoothly switch to a green image from a red image on the same pixel.
In this conventional RGB back-light display, color data written in advance in a memory and having a duration (for example 16 ms) equal to one frame are compressed so as to have a duration (for example 2.6 ms) short of one frame duration and then the compressed data is transferred to individual pixel areas. Light sources corresponding with images conveyed by the compressed data are turned on in synchrony with the compressed data reading time (for example 2.6 ms) as the blanking time. The remaining hold time (for example 13.4 ms) is used as the effective illumination time for display.
With this method, although an image depicted on the display device is turned off via a specified signal during the blanking time (2.6 ms), the dot state of this image just turned off is still held during the holding time (that is, 13.4 ms) on the display with declination of its intensity by a memorizing activity of liquid crystal. In the next frame, when depiction of an image of a different color is required, the foregoing dot state of liquid crystal declines sufficiently to allow the smooth switching to the image of the different color. This enables the smooth and swift switching of multiple color images. Moreover, the intensity of the image brightness is not controlled in this conventional RGB back-light display.